In the packaging art, it is a general desideratum to be able to design containers and lids such that, in each filled container, its storage space is utilized to the most efficient possible extent. It is also of considerable importance that the space--often termed the `headspace`--between the filling goods and the closure (lid) of the container be minimized in order that, when the filling goods include liquid, the space above the surface of the liquid be as small as possibly and thereby the negative action which this space may, in many physical applications, exercise on the enclosed goods be minimized. This requirement applies in particular to goods in which solid matter or bodies are included whose quality runs the risk of deterioration if the bodies are not wholly submerged and surrounded by the liquid. Examples of applications in which such a minimization of this space is of crucial value are containers for the storage of herrings in brine. These demands for minization of the space between the liquid surface and the closure of the container are accentuated in physical applications in which the container has a low proportional ratio between its height and its circumference.
One drawback inherent in the employment of as slight a space as possible between the liquid surface and the opening edges of the open container is that in and/or after the filling operation with filling goods, the liquid may unimpeded run or slop over the opening edge and thereby cause problems in conjunction with the filling of the container.
In particular in containers with a low proportional ratio between the container's height and its circumference--and in which there is a need for but a slight space between the closure and the filling surface, it is difficult to guarantee the opened container sufficient space between the filling surface and the opening edges of the container in order to preclude liquid from slopping over the opening edges, for example when the opened container is set on a table.
In containers which are subject to the requirement of small space between the closure or sealing and the liquid surface, it is a not uncommon occurence that the liquid level will be too high in physical applications in which the filling goods include, apart from the liquid, solid bodies--and in particular when these are added manually (for example in the packing of soused herring). This is because the total volume of the solid bodies added to the container varies from container to container.